title: Epidural and subpial cortico-spinal potentials evoked by transcutaneous motor cortex stimulation during spinal cord surgery.
abstract: Cortico-spinal potentials (CSPs) to transcutaneous motor cortex stimulation were recorded epidurally and subpially in 8 patients undergoing spinal cord surgery. In 6 patients without cortico-spinal tract involvement, a CSP consisted of a direct (D) wave, which was followed by indirect (I) waves at a higher stimulus intensity. The D wave appeared at 25-50% of the maximum stimulus intensity. With increasing stimulus its amplitude levelled off between 10 and 30 microV when recorded epidurally. At high stimulus a prominent indirect potential (I' wave) appeared which followed the D wave after 2.2-3.6 msec. The D and I' wave conduction velocities calculated in 3 cases were identical -65, 70 and 80 m/sec. Subpial records had larger amplitudes than epidural ones but were of the same configuration. In 2 patients with spastic paraparesis the CSP changes were detected below the site of the cord lesion.
authors.affiliation: Neurosurgery Department, University Clinical Center, Ljubljana, Yugoslavia.
authors.forename: B
authors.initials: B
authors.lastname: Prestor
authors.forename: T
authors.initials: T
authors.lastname: Zgur
authors.forename: V V
authors.initials: VV
authors.lastname: Dolenc
mesh_terms: D000293:Adolescent; D000328:Adult; D004558:Electric Stimulation; D004569:Electroencephalography; D004824:Epidural Space / Q000502:physiology; D005071:Evoked Potentials; D006801:Humans; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D010841:Pia Mater / Q000502:physiology; D011712:Pyramidal Tracts / Q000502:physiology*; D011930:Reaction Time; D013116:Spinal Cord / Q000502:physiology* / Q000601:surgery; D013118:Spinal Cord Diseases / Q000503:physiopathology* / Q000601:surgery